The invention relates to crystalline dielectric thin film structures on metallic foils. Such thin foil dielectric systems can be prepared, for example, by depositing PbZrxTiyOz (PZT) thin films on selected metallic substrates such as brass, platinum, titanium and stainless steel foils using sol-gel methods, sputtering deposition methods, or metal-organic chemical vapor deposition.
Lead zirconate titanate (PZT) thin films have attracted considerable interest as potential candidate materials for electronic and optoelectronic applications, such as ferroelectric memory devices, pyroelectric sensor devices, waveguide modulators and acoustic sensors. Most PZT films are currently deposited on silicon substrate with a Pt bottom electrode limiting their range of potential applications. Alternative structures are desired which permit high frequency operation range, low dielectric loss, low ESR, and the potential for embedded capacitor systems.
Previous attempts at depositing dielectric films on metal substrates have been reported in the literature. For example, Saegusa (Japanese Journal of Applied Physics, Part 1, vol. 36, no. 11; November 1997; p. 6888-93) reported on the deposition of non-crystalline (glassy) films of PbZr0.5Ti0.5O3 (PZT) thin films on aluminum, titanium and stainless steel foils. The resulting products, however, do not exhibit the requisite properties needed for commercial applications.
The invention relates to crystalline dielectric thin film structures on metallic foils. Such thin foil dielectric systems can be prepared, for example, by depositing PbZrXTiyOZ (PZT) thin films on brass, platinum, nickel alloys, titanium and stainless steel foils using various methods such as sol-gel processing, sputtering deposition, and metal-organic chemical vapor deposition. The crystalline dielectric films of the invention include single-crystalline, poly-crystalline, and nano-crystalline films, i.e., films with grain sizes varying from nanometer-scale to cm-scale.
The crystalline dielectric thin film structures of the invention exhibit excellent properties for capacitors, including high dielectric constant (∈=400), low dielectric loss (loss tangent of  less than 5%) and low leakage current (below 5xc3x9710xe2x88x927 A at 5V). In addition, the thin film structures of the invention exhibit high frequencies.